Perennial Sweet Pea, Non-native Plants of Sequoia and Kings Canyon National Parks

Non-native Plant Management, Sequoia and Kings Canyon National Parks

Perennial Sweet Pea

Bean Family

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Perennial sweet pea (Lathyrus latifolius) is common in moist disturbed areas throughout California. It is native to Europe. This perennial species can be very tenacious and can spread for considerable distances along waterways.

Identification

Perennial sweet pea is very distinctive on account of the prominent wings or flanges present on the stems. These wings make the stems appear flat and leaf like. The leaves themselves are paired; a branched curly tendril arises from the base of each pair. The flowers are variously colored and are showy, like those of the garden pea. Perennial sweet pea is restricted to moist or disturbed areas in Sequoia National Park.

Look-Alikes

Jepson's pea (Lathyrus jepsonii var. californicus) is a native species that is very similar in appearance to the perennial sweet pea. It has winged stems and showy flowers. However, its leaves are clustered into groups of 10 to 16, unlike the leaves of perennial sweet pea which are borne in twos. Jepson's pea is restricted to wet areas, such as stream banks.

Sulfur pea (Lathyrus sulphureus) is a native that looks superficially similar to the perennial sweet pea. However its stems are round (entirely unwinged) and its flowers are white. It grows in grassy foothill areas.


Perennial sweet pea with flattened "winged" stems. Photo courtesy Boulder County Parks and Open Space.

The common vetch (Vicia sativa) is a non-native annual relative of the perennial sweet pea. It too has showy flowers but its stems are round and it has numerous leaves in each leaf cluster. The common vetch grows in grassy places near disturbed areas.

The surest way to identify perennial sweet pea is by its winged stems and paired leaves.

Natural History

Like most members of the bean family, the seeds of perennial sweet pea are large and full of nutrients; hence, they can remain viable for long periods of time. While one pod can contain only a few seeds, one plant can produce many hundreds of seeds during a growing season.

Management

Two populations of perennial sweet pea are known to exist in Sequoia and Kings Canyon National Parks. One is large and is actively invading Traugers Creek in Sequoia National Park. The other population is in the Ash Mountain Headquarters developed area. Control efforts are scheduled for both populations. Plants will be controlled by completely removing roots by hand, or by using spot treatments of approved glyphosate herbicide.

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